This invention is directed to improvements in non-pneumatic urethane tires. In a non-pneumatic tire a central tunnel can be formed in the tire body which accepts a segment of semiresilient hollow tubing. This hollow tubing maintains beads formed as a part of the tire body in a fixed relationship with respect to side walls on the wheel rim on which the tire is mounted regardless of the width of the wheel rim.
In our applications Ser. No. 37,393 and Ser. No. 906,691 the advantages of non-pneumatic monolithic urethane elastomer tires are described and compared to the disadvantages of pneumatic bicycle tires. Since the non-pneumatic urethane tires do not utilize inner tubes certain characteristics must be incorporated in both the design of and the materials used for these non-pneumatic urethane tires. The tire must be formed of material hard enough to resist abrasion and wear yet soft enough to provide a satisfactory ride. Further, these tires are made with a hollow interior which reduces weight of the tire and improves ride characteristics.
Unfortunately, even though manufacturers utilize standard diameters for wheel rims they have not standardized the width or the depth of the rim. As a result of this urethane tires having hollow interiors can come off of the rim on which they are mounted if they are subject to sufficient forces directed to the tire body which are normal or perpendicular to the plane which contains the tire in the wheel rim. In our application Ser. No. 906,691 we described an H-shaped bead lock insert which alleviates this problem. However, this insert works best when locking grooves are formed in the tire which it fits into. This renders the molding of the tire more complex. Further, this insert must be positioned on the wheel rim prior to mounting of the tire body which complicates the mounting procedure.